Re: [PATCH RFC 2/6] x86/ioapic: add a raw field to RTE struct

[Jan Beulich <jbeulich@xxxxxxxx>]

On 21.04.2022 15:21, Roger Pau Monne wrote:
> No functional change intended.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Once seeing the purpose (in a later patch, I suppose) I certainly
don't mind. We do have a couple of literal initializers, though (see
e.g. the top of ioapic_guest_write()). Do those still compile fine
(warning free) even with old gcc?

Jan

> --- a/xen/arch/x86/include/asm/io_apic.h
> +++ b/xen/arch/x86/include/asm/io_apic.h
> @@ -89,35 +89,38 @@ enum ioapic_irq_destination_types {
>  };
>  
>  struct IO_APIC_route_entry {
> -    unsigned int vector:8;
> -    unsigned int delivery_mode:3; /*
> -                                   * 000: FIXED
> -                                   * 001: lowest prio
> -                                   * 111: ExtINT
> -                                   */
> -    unsigned int dest_mode:1;     /* 0: physical, 1: logical */
> -    unsigned int delivery_status:1;
> -    unsigned int polarity:1;      /* 0: low, 1: high */
> -    unsigned int irr:1;
> -    unsigned int trigger:1;       /* 0: edge, 1: level */
> -    unsigned int mask:1;          /* 0: enabled, 1: disabled */
> -    unsigned int __reserved_2:15;
> -
>      union {
>          struct {
> -            unsigned int __reserved_1:24;
> -            unsigned int physical_dest:4;
> -            unsigned int __reserved_2:4;
> -        } physical;
> -
> -        struct {
> -            unsigned int __reserved_1:24;
> -            unsigned int logical_dest:8;
> -        } logical;
> -
> -        /* used when Interrupt Remapping with EIM is enabled */
> -        unsigned int dest32;
> -    } dest;
> +            unsigned int vector:8;
> +            unsigned int delivery_mode:3; /*
> +                                           * 000: FIXED
> +                                           * 001: lowest prio
> +                                           * 111: ExtINT
> +                                           */
> +            unsigned int dest_mode:1;     /* 0: physical, 1: logical */
> +            unsigned int delivery_status:1;
> +            unsigned int polarity:1;      /* 0: low, 1: high */
> +            unsigned int irr:1;
> +            unsigned int trigger:1;       /* 0: edge, 1: level */
> +            unsigned int mask:1;          /* 0: enabled, 1: disabled */
> +            unsigned int __reserved_2:15;
> +
> +            union {
> +                struct {
> +                    unsigned int __reserved_1:24;
> +                    unsigned int physical_dest:4;
> +                    unsigned int __reserved_2:4;
> +                } physical;
> +
> +                struct {
> +                    unsigned int __reserved_1:24;
> +                    unsigned int logical_dest:8;
> +                } logical;
> +                unsigned int dest32;
> +            } dest;
> +        };
> +        uint64_t raw;
> +    };
>  };
>  
>  /*